Inhibitors of HIV integrase (IN) are being developed as potential anti-AIDS drugs. Although a large number of inhibitors have been reported in the literature, little information has been forthcoming regarding the molecular interactions of these agents with IN protein. One focus of this project is to design and synthesize pharmacological tools to clarify molecular interactions of inhibitors with IN. In one study we prepared biphenyl ketone-containing coumarins as photoaffinity ligands. These were cross-linked to IN and the site of cross-linking was identified by mass spectroscopy and confirmed by mutagenesis and molecular modeling experiments to be distal to the catalytic site at the IN dimer interface. This information should aid in the design of interfacial inhibitors that act outside of the catalytic site. Another important class of IN inhibitors is represented by the aryl beta-diketo acids that are thought to function as metal chelators within the IN catalytic site. In order to elucidate the manner in which these inhibitors interact with IN-DNA substrate complexes, photoaffinity labels were appended onto high affinity aryl beta-diketo acid inhibitors along with biotin tags intended to facilitate isolation and purification of photo-cross-linked products. Photoactivation studies of inhibitors in the presence of IN along with MALDI-TOF mass spectral identification of cross-linked products is ongoing.In other studies, binding of the HIV p6Gag protein to human Tsg101 protein has been shown to be necessary for viral budding and to involve a critical 9-mer "P-E-P-T-A-P-P-E-E" sequence of the p6 protein. We are preparing peptide and peptide mimetic variants of this 9-mer sequence as Tsg101-binding antagonists that may lead to a new class of viral budding inhibitors. One approach was to replace the Pro4 residue with N-substitued glycine (NSG) residues (termed "peptoids"). However, this is synthetically problematic. therefore, we resorted to a new family of peptoid variants that incorporate hydrazone amides as NSG surrogates. These can be preparede readily in library fashion by reacting a series of aldehydes with a single HPLC-purified hydrazide precursor following cleavage from the solid-phase resin. Reduction of these hydrazones to N-substitued "peptoid hydrazides" affords a facile route to library diversification. These studies are advancing the design of Tsg101 binding inhibitors.